AR-2ax's......short road trip...

[Chuck V]

This thread has been fun to watch. If I didn't have a full queue of projects (a pair of Heathkit W5M's at the moment), my pair would be apart by now!!

I'll get to them this winter.

[JKent]

The 2ax's are up and running. Boy, they bring back a lot of memories of yester-years

Sound excellent considering they're sitting on the kitchen table.

It's amazing how every model has their unique sound. The 9's, LST's, LST-2's, 3a's, 2ax's and 4x's all sound wonderful but different.

Beautiful work John, as usual.

I've had a number of speakers pass through here (I fix 'em up, listen for a while, then sell them). Had 2 pair of AR-2ax--one later with the foam surrounds (my first re-foam job!) and an earlier pair just like yours. Those are the speakers (along with the KLH Fives) I most regret having sold. They just sounded right. And I agree with Roy that the original 10" woofer with the cast aluminum frame/alnico magnet is the best.

Fortunately my AR-3/3a speakers that replaced the 2-ax's also have the early cast aluminum/alnico woofer (12" of course). And there's another pair in my "pile" that also sounds good: the 2a, in lacquered Mahogany, with the cast aluminum/alnico woofer. Those were slated for a re-cap but when I saw they had the old oil-filled caps I measured them, found them to be spot on, so they are staying. I may replace the pots with stepped attenuators and coat the surrounds with Roy's glop, Have to repair the cracked Masonite grilles and then there's the problem of where to put them....

The point is, those speakers also sound terrific. I "thought" the angled mids must be inferior to the single mid in the 2ax but they sound really good. Probably a bit more sensitive to placement that the 2ax but placed horizontally on a shelf as they were designed to placed, very very nice speakers.

So many speakers, so little time & space

Sorry to ramble. Keep up the good work!

Kent

[xmas111]

Thanks Kent!

No doubt the 2ax's sound absolutely wonderful.

I think I'm going to take the 2ax's to work and put them in my office. I just don't have any more room here at the house. Still have the LST-2's sitting upstairs collecting dust.

The Heathkit amp at work has two speakers outputs with a A/B/AB switch. I can switch between the 4x's and the 2ax's for the hell it.

There's a guy who's selling on Clist a set of 2ax's for $150.00 about 15 miles form here. They've been listed for while and I suspect he'll take less. I was thinking of scooping them and try the 2ax's stacked.....I must refrain.....I must refrain....

[xmas111]

The 2ax's are all setup and running at my office.

Such a shame I only get to listen to them on Saturday's.

Been a enjoyable project. Now on to that little RCA Victor 45J record changer.....

John

[ra.ra]

The 2ax's look great and fit those shelves well, but now your poor little 4x's are homeless.

Now, do tell ......... exactly how many of these Heathkit receivers do you have?

[xmas111]

The 2ax's look great and fit those shelves well, but now your poor little 4x's are homeless.

Now, do tell ......... exactly how many of these Heathkit receivers do you have?

Don't worry I'll find a place for the 4x's....they're just to good to let sit around.

Love Heathkit stuff. The first Heathkit I built was the AR-15 receiver. My parents gave it to me as a Christmas gift when I was 16. That kit was a brute!

That receiver is long gone, not even sure what happened to it.

Long story short....a few years ago I got the bug to get another AR-15. Ended up getting three of them and rebuilt them all.

Also got the separates of the AR-15 too. The AA-15 amp and AJ-14 tuner.

My brother had my old Heathkit AR-1500 receiver which he gave back to me a couple of years ago. He hadn't used it in years. That's all rebuilt.

Anyway. I've got way to much Heatkit stuff along with other stuff. Got to start selling it, just have to get off my lazy ass and do it!

Attached a picture of the inside of the AR-15(can't find my picture. Found this one online) along with the rest of my stuff laying around.

John

[vrm71]

John,

Your 2Ax's turned out excellent!

I am in the middle of restoring a pair myself and just received the same Russian? rheostats (shipped from Pentod.com / Bulgaria) that you used as well!

I have 2 mismatched woofers, both AR, but one is cloth surround and one foam surround dated Dec of '69 and am missing one "a" pin and one AR Inc. badge. I will try the mismatch woofers first, as I have had it re-foamed, and if that doesn't pair well I will purchase a matching cloth surround woofer. I figure a '69 AR 10" woofer was worth re-foaming if not for this speaker then for someone whom can use it.

Hope mine turn out as well as yours!

Thanks for documenting your restoration as it led me to the replacement rheostats, one of mine was so corroded the wiper tip completely disintegrated whilst trying to clean and deoxit.

[xmas111]

am missing one "a" pin and one AR Inc. badge

Thanks vrm71.

You can contact our member, JKent for the AR logo. He makes an excellent one I know you'll be happy with.

I don't know if he makes the "a" but you can get an repo here....little pricey but that's the price we have to pay when working on vintage speakers.

http://www.ebay.com/itm/ACOUSTIC-RESEARCH-ORIGINAL-AR-2A-LETTER-a-LOGO-PLATE-REFURBISHED-/160962607912

Hope this helps you out with your restoration project. And keep us to date with it.

Good luck with it.

John

[RoyC]

am missing one "a" pin and one AR Inc. badge.

Kent has both items, but is traveling for awhile. If you need them sooner, I have some as well. Send me a PM if I can be of assistance.

Roy

[xmas111]

Bad news with the 2ax’s. I was listening to them Saturday when I notice the woofer was making some odd sound. Sounded like something was hitting the cone on the inside of the speaker.

I took off the grill and couldn’t see anything obvious then I started to think about what Roy had mentioned in an earlier post about the Masonite rings coming loose.

Well sure enough the ring under the surround was lifting off. Not the whole ring but about half. Decided to pull the speaker and check the spider. Sure enough it had totally separated from the frame.

I checked these before reinstalling them and they seemed fine. I guess the pressure build up in the cabinet was enough to finally cause the failure. I wonder how long before the other one does the same.

Going to take it home tonight to repair it. One quick question, what would you guys recommend to reglue it? I have some Loctite 2 part epoxy and some glue Vintage-AR supplied with surrounds I bought a while ago. The glue from Vintage-AR isn’t the standard white glue it’s translucence/ yellowish. Or should I look for something else.

A few pics attached.

Thanks,

John

[rjr513]

John, did you have any glue left over from reconing of your LST woofer? that would work?

[xmas111]

John, did you have any glue left over from reconing of your LST woofer? that would work?

Hi Ron,

As a matter of fact I do. Thanks for the suggestion.

John

[Chuck V]

Ok, with my workbench clear, I decided it's time to tackle the AR's. I hope it's ok to jump onto this thread, if I committed a "faux pas", please let me know. I've taken the first one apart, and all the drivers passed the ohm test. I've removed the woofer and mid, and I was hoping some might review my pix and lend their experienced thinking. I do a couple (ok, a few) questions...

It appears my speakers used rock wool, is it recommended to new fiberglass or reuse the rock wool? As per the AR3ax restore guide, I've saved the rock wool and Kempac in a plastic bag.

I played the speakers at low volume and they produced sound, I know the woofer needs it's Masonite ring reglued, and cloth surrounds treated, but should I check the voice coil and spider assembly? I assume the answer is yes, but what is the best way to look in there (my pix of the back of the woofer should explain)?

Do the potentiometers look like they can be cleaned up and used? My instincts tell me yes, but I'd Like more experienced folks weigh in.

Lastly, the tweeters look like they are well secured, and understanding how delicate the wires are, should I work on the cabinets with the tweeters in place (well protected, of course)?

Thanks to any and all for advice/suggestions

[xmas111]

Chuck,

I can't say if you should replace the rock wool or not. I not sure what difference it would make. Others may have more information about it than me. On the one's I did I reused it

The pot's look like a mess to me. I've never had much luck repairing them. There was always a dead spot right were the wire attaches to the rivets. As you can see earlier in the thread I ended up using the Russian pots. They work very well and a lot cheaper than the Ohmite pots.

The guy on ebay only has 3 of the Russian pots left. http://www.ebay.com/itm/25W-15-OhM-CERAMIC-WIREWOUND-POTENTIOMETER-PPB-25G-SOVIET-MADE-ORIGINAL-BOX-/151126528520?pt=LH_DefaultDomain_0&hash=item232fd7d208

There's a ton of threads here about using the Ohmite pots. The only problem with using them is you have to build some type of box to cover them up or else the stuffing will get between the wire and the wiper and cause problems.

I had a problem getting the tweeter out too. There was no way I was going to leave it in and take a chance of damaging it. What I ended up doing was putting a block of wood under it then with a short piece of 2X4 pushed out. I was amazed how much it took to push it out. If you decide to leave it in be very very careful.

I had one of those wires from the tweeter break while removing it from the terminal......I was pissed! It broke right where it clamped into the terminal. I had to loosen the terminal and rotate 90º to get it to go back in when reinstalling it.

Good luck with you restoration.....you're going to love the 2ax's!

John

[xmas111]

Reglued the woofer last night with the glue I used to recone the LST woofers. Looks like it went well.

Taking it back to work tomorrow to pop it back in. I'll let you know how it sounds......keeping my fingers crossed!

UPDATE: Put it back in today and works like a Charm! Back in business again.

John

[ra.ra]

Glad to hear you got that woofer glued back together with a fairly simple repair. It was almost funny that right after you finished your immaculate restoration, a different and unexpected weak point (the original woofer adhesive) in these 45 year old speakers gave up the ghost immediately after you got them up and running.

While looking at Chuck's corroded pots, I wanted to add this note to show my recent efforts at restoring four rather crunchy pots from a pair of 2ax's that were graciously donated to me by a generous CSP member (thx, John).

Each of them showed substantial build-up, and there were various degrees of corrosive pitting on the metal sweeps. Some of these I chose not to re-use, and instead replaced them with better sweeps from some other abandoned pots. The third pic shows the pots submerged in the salt/vinegar solution (thx, tmadblue) and you can see how with just a little time, the chemical treatment alters the color of the corroded metal areas. After the soak and a good rinse, I use brass or stainless metal brushes for abrasion, and possibly a fine wet/dry paper or emery cloth.

Before re-assembly, I first use a silicone spray and later apply a coating of dielectric grease. It is a lot of fussy PITA work, but these pots will now get re-used. They are old and not perfect, but when tested with meter, they all deliver a nearly complete and smooth variable range of resistance from zero to fifteen ohms.

Even though I don't really mind conducting this procedure, I am still very interested in trying the Russian pots some day, or maybe even the L-pads with resistor.

[xmas111]

Nice job on those pots Rob! Pretty skilled hands you have. I was going to throw them away because I don't have the patience you certainly have for such work.

Professional looking pics too.

If I had a choice between the original pots and the Ohmites or Russian pots I'd take the originals any day. Having to build a container to cover the Ohmites or Russian pots is a real PITA. There's not a lot of room between the pots and the terminal screws for the container.

The L-Pads are ok and easy to install but still not up to the original AR designer's intentions.

Again great job and restoring those......can I have them back now?

John

[RoyC]

The L-Pads are ok and easy to install but still not up to the original AR designer's intentions

John

I have to disagree, John. If today's L-pads were available way back when, they would have been used. When AR introduced the AR-3a Limited in the early 90's, common 8 ohm L-pads were used, not 15 ohm potentiometers. Adding a simple, inexpensive, 25 ohm resistor in parallel with the mids and tweeters when using L-pads will provide the same electrical and sonic performance as a 15 ohm pot at all typically used settings (1st half of the rotation). When using an L-pad, the back is already covered, and it will last longer than an original pot (refurbished or otherwise). I was dealing with crappy AR pots as early as the late 70's. They are simply prone to corrosion, and were the weakest part of the AR design. There is a very valid reason we saw the pots removed from all later models, including the AR-3a Improved, AR-11, etc.

When absolute "authenticity" is desired for reasons other than sound, I always use the original pots when/if they can be made perfect. I will NOT, however, use AR pots which had developed heavy green corrosion resulting in pits and drop-outs. For MY personal use, and for those folks who don't require *collectors* authenticity, I use the L-pad/resistor combo. The cost and inconvenience of installing Ohmmites, etc, is unnecessary in most cases, imo.

As an aside, there are instances where L-pads can actually provide a sonic advantage. I sometimes recommend the use of an L-pad, without the added 25 ohm resistor, for use with original AR tweeters. These drivers are often diminished in output, and the L-pad will provide a needed boost to the high frequency response...and, perhaps, bring the response closer to the day it left the factory!

Larry/"Vintage AR" and AB Tech have sold many hundreds of L-pads as replacements for the pots without complaint or failure...To be clear, however, I always advocate the use of the 25 ohm parallel resistor for at least the midrange circuit to maintain the proper tonal balance.

My reason for jumping in here is I don't believe people reading this forum should be led to believe that using L-pads instead of 15 ohm pots will result in an inferior outcome. It is an option as viable as Ohmmite and Russian pots, with less cost and complexity...although I should add that the typical high selling price of the glorified L-pad "kits" on Ebay is not the best way to go. If L-pads are used it is best to purchase them (and resistors) from websites like Parts Express, Madisound, Erse, and Meniscus.

Roy

[xmas111]

Roy,

Thanks for straightening me out. Sometimes these old fingers type without thinking.

I hope I remember your advice about using the L-pad without the 25 Ω resistor for use with original AR tweeters if (when) I restore anymore AR's.

John

[RoyC]

Roy,

Thanks for straightening me out. Sometimes these old fingers type without thinking.

I hope I remember your advice about using the L-pad without the 25 Ω resistor for use with original AR tweeters if (when) I restore anymore AR's.

John

No problem, John...I just wanted to clarify the options a bit. Your beautiful and thorough restorations serve as an inspiration for anyone interested in bringing these beasts back to life!

I should add that it is the old 3/4" dome tweeters that often benefit from L-pads without the added resistor. For all other tweeters (such as the one used in the 4x) I use the resistor with the L-pad.

Roy

[Chuck V]

Glad to hear you got that woofer glued back together with a fairly simple repair. It was almost funny that right after you finished your immaculate restoration, a different and unexpected weak point (the original woofer adhesive) in these 45 year old speakers gave up the ghost immediately after you got them up and running.

While looking at Chuck's corroded pots, I wanted to add this note to show my recent efforts at restoring four rather crunchy pots from a pair of 2ax's that were graciously donated to me by a generous CSP member (thx, John).

Each of them showed substantial build-up, and there were various degrees of corrosive pitting on the metal sweeps. Some of these I chose not to re-use, and instead replaced them with better sweeps from some other abandoned pots. The third pic shows the pots submerged in the salt/vinegar solution (thx, tmadblue) and you can see how with just a little time, the chemical treatment alters the color of the corroded metal areas. After the soak and a good rinse, I use brass or stainless metal brushes for abrasion, and possibly a fine wet/dry paper or emery cloth.

Before re-assembly, I first use a silicone spray and later apply a coating of dielectric grease. It is a lot of fussy PITA work, but these pots will now get re-used. They are old and not perfect, but when tested with meter, they all deliver a nearly complete and smooth variable range of resistance from zero to fifteen ohms.

Even though I don't really mind conducting this procedure, I am still very interested in trying the Russian pots some day, or maybe even the L-pads with resistor.

pots before:after.jpg pots corrosion.jpg pots soak.jpgjohn's pots.jpg

Wow, those pots look amazing. I took a run at cleaning up one of the pots using a Dremel tool. While I was able to get it cleaned up, it doesn't measure well. Luckily, I've got a friend who has 4 pots that are clean and test well.

I've finished the work on cleaning up the cabinets. I Used Murphy's Oil Soap with a scotch brite pad to get the gunk and years of grime off. The scotch brite does a nice job of rubbing out the small scratches and stubborn marks. While there are a few deeper scratches, they are not so offensive that I was willing to put sandpaper to them.

After the cleaning, I used Howard's Feed and Wax. I've had good luck with it in the past and I was happy with these results. I've had good luck warming up the feed and wax a bit (placing the bottle in a pan of hot tap water) before applying.

[Chuck V]

A quick update...I got the pots from my friend, and together with what I had I was able to make 4 good ones. I finally got one reassembled tonight, hooked it up and gave it a few minutes with Stevie Ray Vaughan.

It appears the "return" on the woofer is good, and all drivers are working. I'm hoping to enjoy the pair this weekend. After the second one is done, I'll move on to finding or making new grill frames (the originals are broken in a few places).

Any thoughts on the best type of material to make new grill frames?

[ra.ra]

From what I have seen, almost all of the grille frames from the classic AR's consist of 1/4" hardboard, more commonly known as Masonite. Some grilles from small early speakers (e.g. AR-4's) had frames made from 1/4" plywood or slats of softwood, but these are not nearly as robust as the more common Masonite frames. The cut-out openings in the frames always correlated with the size and placement of the drivers in the speaker cabinet.

1/4" masonite is manufactured in tempered and untempered versions. I believe tempered may have even a bit more resistance to moisture absorption and exhibits superior stiffness. Downside might be that it is more difficult to receive a staple for the grille cloth.

Attached is partial note from AR-3a restoration guide. If you have access to a Home Depot, I think they sell some 1/4" Masonite in small pre-cut sizes that may make the process a bit easier than lugging around a 4' x 8' sheet.

Oops ..... almost forgot to say that SRV always makes a fine choice for a first listen - - - I had the good fortune to meet him many years ago.

[xmas111]

I have always been frustrated when replacing the cloth on AR speakers. ra.ra is right about being tough to staple into the masonite, it's a bitch with regular staplers. Actually almost impossible.

I'd staple the cloth then take a small hammer and try to get the staples the rest of the way in. Probably wasted more staples than I got to go in.

When I did the 2ax's a few months ago I said I've got to find a better way to get the job done.

Went to Home Depot and looked at all the manual staplers. I wasn't going to spend hundreds of dollars on a power staplers for something I was going to hardly ever use. I decided to go with this one: http://www.homedepot.com/p/Arrow-Fastener-Red-Staple-Gun-T50RED/202352407?N=4sh%2FNtk-All%2FNtt-staplers%3FNtx%3Dmode%2Bmatchall%26NCNI-5#.UqRcwk1CqHs

It get's lousy reviews but I figured for $25.00 it was worth a try. Well it worked perfect for me! Drove those sucker right in. Just make sure you hold it very firm against the masonite while stapling.

So if you decide to go with masonite you might want to try that stapler......might save you a lot of headaches.

Good luck with the rest of your project. Should be well worth your efforts.

John

[JKent]

When absolute "authenticity" is desired for reasons other than sound, I always use the original pots when/if they can be made perfect. I will NOT, however, use AR pots which had developed heavy green corrosion resulting in pits and drop-outs. For MY personal use, and for those folks who don't require *collectors* authenticity, I use the L-pad/resistor combo. The cost and inconvenience of installing Ohmmites, etc, is unnecessary in most cases, imo.

My reason for jumping in here is I don't believe people reading this forum should be led to believe that using L-pads instead of 15 ohm pots will result in an inferior outcome. It is an option as viable as Ohmmite and Russian pots, with less cost and complexity...although I should add that the typical high selling price of the glorified L-pad "kits" on Ebay is not the best way to go. If L-pads are used it is best to purchase them (and resistors) from websites like Parts Express, Madisound, Erse, and Meniscus.

All good points Roy and of course I have, on your advice, used the L-pad/resistor combo. Easy, cheap, trouble-free. I used Ohmites in my 3a's for a "more authentic" approach and they were definitely not worth the hassle. I had bought them on a surplus close-out for $7 each so the cost was not a consideration (should have bought more but that's water over the dam).

For those who want something fancier than L-pads, the stepped attenuators seem like a good option. I plan to try those when I get around to restoring my 2a's.

ChuckV: Beautiful looking cabinets! To return to your question about rock wool; if that's what you have do NOT re-use it. Rock wool is typically light brown in color while FG is usually yellow or pink. See page 21 of the AR-3a restoration booklet. Rock wool does not have the sonic benefits of fiberglass and although it is not mentioned in the restoration guide, the sulphur in rock wool causes excessive corrosion of the pots (and maybe the back of your woofer magnet too, judging by the photo). This was addressed in a paper by John O’Hanlon, Kenyon MacLeod and Gary Chandler, Corrosion in Acoustic Research Potentiometers.

Replace rock wool with fiberglass. Common building insulation is perfect and Lowe's sells handy little bags of white Johns Manville fiberglass that weigh (IIRC) 9 oz each. I forget how much goes in each 2ax--somewhere between 20 and 28 oz IIRC--but Roy can probably tell you the correct amount to use.

Kent